1. Field of the Invention
The present invention pertains to the art of cooking appliances and, more specifically, to a cooking appliance in the form of a smooth surface gas cooktop having a combination, electric ignition/turndown system.
2. Discussion of the Prior Art
In the art of cooking appliances it is known to provide a smooth cooking surface upon which a variety of cooking operations can be performed. Typically, the cooktop includes a plurality of independently controlled cooking or heating zones mounted upon an oven range or, alternatively, in a kitchen countertop, island assembly or the like. In general, arranged below each of the plurality of cooking zones is an associated heat source which, upon activation, transmits heat to the cooking surface for performing a selected cooking process. In most applications that utilize a smooth cooking surface, the heat source is a sheathed, resistive heating element of a type commonly used in electric cooking applications. However, manufacturers are producing “gas under glass” or smooth surface cooktops using gas as a heat source.
In contrast to electric heating elements, mounting gas burners below a smooth cooktop surface requires special design considerations. Namely, gas burners require an air in sufficient amounts to fully combust the available gas. Less than full combustion results in emissions that exceed accepted regulatory standards. Therefore, gas under glass systems generally operate with a forced combustion, induced draft system which burn with a clear flame. However, as the flame is in all accounts invisible, it is difficult for a consumer to determine when a particular burner is in operation. Accordingly, several manufactures include a wire filament or re-radiant coil mounted adjacent to the burner which, when heated, glows. In this manner, the consumer is provided with a visual indication that a particular cooking zone is activated. In addition to the re-radiant coil, manufactures may also include a temperature sensor which signals a control to provide an indication, such as by illuminating an LED, to the consumer that a particular burner is in operation or has recently been operated.
A more pronounced problem associated with gas under glass systems is maintaining stable performance at low gas input or turndown conditions. Since the gas burners operate with forced air combustion, maintaining an adequate fuel/air ratio at low heat levels is difficult. Typically, when low heat is selected, the flame can starve due to an insufficient supply of air. As a result, the consumer will be unable to reliably simmer or cook foods using a low heat setting. This can make the gas under glass arrangement unacceptable to most users. Therefore, based on at least these reasons, there exists a need in the art for a gas under glass cooktop capable of maintaining stable performance at low gas or turndown conditions.